Autofrettage to Offset Coefficient of Thermal Expansion Mismatch in Metal-Lined Composite Pipes

Author(s):  
EJ Barbero ◽  
EW Wen
2021 ◽  
Author(s):  
Payam Emadi

The increased use of magnesium alloys with improved mechanical properties is a prominent strategy towards increasing fuel efficiency of vehicles and decreasing emissions. This study investigates the grain refining efficiency and fading of MgB2 micro- and nano-particle added Pure Mg and AZ91E. Addition of micro and nano-sized MgB2 provided a reduction in grain size for Pure Mg and AZ91E. Enhanced heterogeneous nucleation and grain growth restriction was believed to be the source of refinement. Fading was observed for both Pure Mg and AZ91E, with the nano-particle added castings showing an increased resistance. The elongation of the Pure Mg samples showed improvements, whereas no improvements for UTS and YS was seen. The improved ductility was believed to be due to the grain refinement and coefficient of thermal expansion mismatch. The AZ91E samples did not show improvements in mechanical properties. This was believed to be due to stress concentration from Al-Mn intermetallics.


2021 ◽  
Author(s):  
Payam Emadi

The increased use of magnesium alloys with improved mechanical properties is a prominent strategy towards increasing fuel efficiency of vehicles and decreasing emissions. This study investigates the grain refining efficiency and fading of MgB2 micro- and nano-particle added Pure Mg and AZ91E. Addition of micro and nano-sized MgB2 provided a reduction in grain size for Pure Mg and AZ91E. Enhanced heterogeneous nucleation and grain growth restriction was believed to be the source of refinement. Fading was observed for both Pure Mg and AZ91E, with the nano-particle added castings showing an increased resistance. The elongation of the Pure Mg samples showed improvements, whereas no improvements for UTS and YS was seen. The improved ductility was believed to be due to the grain refinement and coefficient of thermal expansion mismatch. The AZ91E samples did not show improvements in mechanical properties. This was believed to be due to stress concentration from Al-Mn intermetallics.


Author(s):  
Tumininu Olatunji ◽  
David Huitink

Abstract Electronics packaging development is greatly dependent on the magnitude of interconnect and on-chip stress that ultimately limits the reliability of electronic components. Thermomechanical strains occur because of the coefficient of thermal expansion mismatch from different conjoined materials being assembled to manufacture a device. To curb the effect of thermal expansion mismatch, studies have been done in integrating compliant structures between dies, solder balls, and substrates. Initial studies have enabled the design and manufacturing of these structures using a photolithography approach which involves an increased number of fabrication steps depending on the complexity of the structures. This current study involves the fabrication of these structures using a different approach, utilizing additive manufacturing that reduces the number of fabrication steps required to obtain compliant geometries, while also providing a platform for unique compliant structures. This paper discusses the method of fabrication and analyzes the properties and effects of these interconnect structures on a die. Structural finite element thermal cycling simulations between −40 to 125°C show about a 115% increase in the solder joint fatigue life. Additionally, fabricated test structures created directly on a PCB were experimentally characterized for compliance using a micro-indenter tester, showing a mechanical compliance range of 265.95 to 656.78 μ/N for selected design parameters to be integrated into a test vehicle.


2013 ◽  
Vol 46 (3) ◽  
pp. 823-825 ◽  
Author(s):  
Cody R. Morelock ◽  
Matthew R. Suchomel ◽  
Angus P. Wilkinson

GE-7031 varnish, a commonly used low-temperature adhesive and electrical insulator owing to its high thermal conductivity and mechanical strength at low temperatures, was used as a sample matrix for low-temperature powder X-ray diffraction measurements of the negative thermal expansion (NTE) material ScF3. When ScF3powder was mixed with GE-7031 varnish, an unexpected cubic to rhombohedral phase transition in the ScF3sample was observed at ∼50 K, and it exhibited smaller low-temperature unit-cell volumes than samples without the varnish matrix. Experimental observations and quantitative estimates suggest that these anomalies are the result of stress induced by a thermal expansion mismatch between the varnish matrix (large positive coefficient of thermal expansion, CTE) and ScF3(quite large negative CTE). The use of GE-7031 varnish as a sample matrix for low-temperature measurements should be approached with caution if a large thermal expansion mismatch is expected.


Author(s):  
J. Cooper ◽  
O. Popoola ◽  
W. M. Kriven

Nickel sulfide inclusions have been implicated in the spontaneous fracture of large windows of tempered plate glass. Two alternative explanations for the fracture-initiating behaviour of these inclusions have been proposed: (1) the volume increase which accompanies the α to β phase transformation in stoichiometric NiS, and (2) the thermal expansion mismatch between the nickel sulfide phases and the glass matrix. The microstructure and microchemistry of the small inclusions (80 to 250 μm spheres), needed to determine the cause of fracture, have not been well characterized hitherto. The aim of this communication is to report a detailed TEM and EDS study of the inclusions.


Alloy Digest ◽  
1987 ◽  
Vol 36 (8) ◽  

Abstract NILO alloy 36 is a binary iron-nickel alloy having a very low and essentially constant coefficient of thermal expansion at atmospheric temperatures. This datasheet provides information on composition, physical properties, elasticity, and tensile properties. It also includes information on high temperature performance and corrosion resistance as well as forming, heat treating, machining, joining, and surface treatment. Filing Code: Fe-79. Producer or source: Inco Alloys International Inc..


Alloy Digest ◽  
1971 ◽  
Vol 20 (1) ◽  

Abstract UNISPAN LR35 offers the lowest coefficient of thermal expansion of any alloy now available. It is a low residual modification of UNISPAN 36 for fully achieving the demanding operational level of precision equipment. This datasheet provides information on composition, physical properties, hardness, and tensile properties. It also includes information on high temperature performance and corrosion resistance as well as forming, heat treating, machining, and surface treatment. Filing Code: Fe-46. Producer or source: Cyclops Corporation.


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